Multiparty fair PDF contract signing method based on block chain

Abstract

The invention relates to a multiparty fair PDF contract signing method based on a block chain. Participants comprise a plurality of contract signers P<1>,... and P<n>, a trusted third party (TTP) andblock chain nodes. The method comprises the steps that the P<1> generates a verifiable encryption signature VES<1> of a contract, calculates a hash context CTX<1> of contract content, generates elements GE<1> of a group key negotiation agreement GKA, packages the VES<1>, the CTX<1> and the GE<1> into block chain transaction and sends the block chain transaction to any block chain node; a P verifies VES<i-1> of a P<i-1>, wherein the i is greater than 1 and is smaller than or equal to the n, after the verification is successful, the P generates a new VES, CTX and GE, and sends theVES, CTX and GE to any block chain node through transaction; after the P<n> finishes operation, a P<j> calculates a group encryption key GK, wherein the j is greater than or equal to 1 and is smaller than or equal to the n, the P<j> encrypts a digital signature of a PDF document to form a ciphertext C<j>, packages the C<j> into the transaction and sends the transaction to the block chainnode; the P<j> queries block chain data, decrypts the block chain data through utilization of the GK and then combines the block chain data into a complete PDF contract; and if the P<j> does not obtain the block chain data after the P<j> is overtime, the P<j> communicates with the TTP to process an exception. According to the method, the dependence on the TTP is relatively weak, and the efficiency is relatively high.

Description

technical field [0001] The invention relates to the field of information security, in particular to a block chain application technology for completing multi-party fair PDF contract signing. Background technique [0002] Fair contract signing means that two or more parties participating in the contract signing can either get a contract signed by all parties at the same time, or neither can get a valid contract signature. This problem has been studied very early, and it has always been concerned in the field of cryptographic application technology. From the early signing of a fair contract between two parties to the later signing of a fair contract based on a third party, people have given a variety of interesting and effective solutions. plan. [0003] However, when the theoretical research results are applied to PDF contract signing, there are obstacles. PDF contract signing is designed to be a sequential signature technology of all parties, that is, the signature of the ...

AI Technical Summary

Problems solved by technology

However, in this method, the subsequent contract signer needs to transmit the digital signature of the previous contract signer, and TTP needs to participate in the pro...

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